Mercury switch



Nw. 15, 1925. www@ R.L.KNUTSSON MERCURY SWITCH Filed QC.416, 1924 Eil/767m; R096? lf, Jain/@$50724 @y ma M mm Patented Nov. 16, 1926.

UNITED sp'rArss N T F F l QE BOG-EB KNUTSSON, OF EOCKFOBD, ILLINOIS, ASSIGNOR 0F ONE-HALF TO EDGAB'C.

ALLEN, i OF ROCKFQRD, 'ILLYNOIS Mnacuan swrrcn.

Application mea october 1e, 1924. serial No, 743,951.

This invention relates to mercury switches and particularly to a mercury switch having a construction permitting it to be readily connected to a suitable socket in order to ob- Btain quick and easy electrical connection thereto. The growing demand for mercury switches in various arts has resulted in uses therefor which call for mounting a switch in a movable part, the motion of which lo serves to actuate the switch. In such uses it is, of course, necessary to have electrical connection thereto and frequently the character of the switch mounting makes it difficult to secure a simple arrangement for a l proper and eiiicient yelectrical connection to a switch.

It is the object of the present invention to provide amercury switch construction adapted to permit electrical connection thereto by a plug and a socket relation.

A particular object of the invention is to provide a mercury switch capable of using a standard bayonet socket of the type employing a single central contact. Y Y

A further object of the invention isl to provide a switch presenting generally at its external surface an insulating medium.

In the drawings, Figure 1 illustrates af switch and a socket in separated relation.

so Fi 2 shows a longitudinal section of a switc insulating tube.. v

Fig. 3 shows a modified form of the switch in Fig. 2 in which a meta lic band replaces the metallic thimble.

Fig. 4i is a fragmentary view like Fig. 3 -showing a modified construction of the metallic band.`

Fig. 5 is a cross section of the switch of ae Fi 2 on the line -lfthereo he body of the switch consists of a tubular open-ended cylindrical casing 6 of a suitable insulatin material, such as fiber or bakelite, whic may be molded to the reas quired form as shown in Fig. 2. The casing 6 has a metallic thimble or lining? on its interior which serves as one contact to the mercury. The thimble may be flared or expanded at its open end 8 and thus molded sa into the wall et the casing 6 to form a unitary switch body 'with a metallic lining. At one end of the casing there Ais a plug l? et insulating material such as ber or bakelite. The plug lits tightly within the opening of te the tubular member 6 and is provided with 'the plug has a centrally 'located having a metal thimble within an an overlapping flange .10,'the edge of which lies flush Vwith the outside of the casing thus forming aY continuously cylindrical switch body.V On the interior of the cas-ing, rounding projection 11 through the center of which a single contact l2 extends. I rlhe contact projects from the plug to a slight extent into the interior of the casing in orderto :iliord suiiicient surface to make `contact. with a globule of mercury 13. At the outside of the cap or plug 9 a depression 1-1 is formed 'centrally in the material thereof into which the other` end of the 'contact 12 extends. Al

thin metallic washer 15 is placed inthe bottom of the depression 14, over which solder 16 is placed to fill the depression, the solder preferably protruding Ato a slight extent above the flat surface of the plug end. lins 17 and 1,8 pass through'the casing 6 into the plug 9 to secure the partsvtogether and also to provide attaching means for use in the socket illustrated. In the pzesent instance the Apins pass through the metallic thimble andthus form an electrical connect-ion to the ground.

FigL'l illustrates a standard single-contact bayonet socket comprising a tubular mem- -ber 19 to receive tlie switch herein disclosed.

A. single spring-pressed` contact 2O located `centrally of the socket makes contactl with the solder 16. Bayonet slots'21 and 22 of usual construction receive the pins 17 and 18 in a well known manner, thereby completing electrical connection to the switch through the solder 16 and the pins 17 and 18'.

In Fig. 3 there is shown a modification of i the switch above vdescribed in which a portion of the metallic lining is eliminated. vA

lining ring 23 of conducting material, preferably metal, is located in the vicinity of the contact 12 so that the mercury 13 will have electrical connection therewith when the switch is tilted to place the contact end theref of lowermost. As in the first instance elec,- trical connectionis made through pins 17 and 18. lt will be observed that the ring 23` has an enlarged portion 2li: thereon by which it is. rigidly held in the casing 6, the same being preferably moulded in a` bakelite casing. ln this inst-ance, the ring 23 'is setinto the body o the casing 6 with its opening flush .with the interior thereof, therebprovidine7 the receiving opening for the piug. ln tlE1`i'ig.l-, a Slightly moditied ring lll@ construction is shown, the ring having a portion projecting into the interior of the casing forming an annular' ledge or ridge 25 therein.

In operation 'the mercury flows from end to end as the switch is tilted.l Upon reaching the contact end of the switch the mer-y cury has little tendency to bounce away therefrom because of the rounded or inclined form of the projection 8. rThis assures a ready functioning of the switch without a prel'in'iinary cutting oli' of current which might result if the mercury should jump away from the end because of impact therewith. In thc form shown in Fig. 2

the usic of a metallic thimble or lining withinv the insulating cas-ing materiallyl strengthens the structure ot' the switch and thus adapts the same to a variety of uses.v In the form shown in Fig. 3 the ring 23 performs the electrical functionsl of the metallic thimble 7, the elimination of which lowers the cost of manufacture of the switch. In

both instances it will be observed that. the

switch receives its two electrical connections through the socket shown in Fig. 1, yet the switch body itself is comprised entirely of insulating material except at .the` contacts 16, 17 and 18. Thus, Atlieswitch maybe mounted in a movable body without. danger' ot' vgrounding through the switch casing.

The annular formof one contact encircling the other permits the switch to bemounted without/ the necessity ofV having a particular side thereof uppermost. 'Ihus the necessity` contact in the casing at said end passingtherethrough to the interior of the casing in I the vicinity of said metallic lining,lt he outer neoaaoc end of said contact being centrally located on said end of the casin andadapted :tor electrical connection wit the 'central contact of the socket, Vmercury insaid casing,

`and a pin projecting outwardly from said casing for engagement with the bayonet slot of the socket, said pin passing through said casing to touch said lining whereby to edect electrical connection thereto.

2. A quick-detachable mercury switch adapted for insertion into abayonet-slotted socket .having a single central contact, said switch comprising, in combination, a metallic thimble, insulating material covering and `enclosing said thimble, a single contact extending through said material into the interior of the casing adjacent to one end of the thimble, the outer end of said contact being centrally locatedl on the end of the casing and adapted for electrical connection with .the central contact of the socket, mercury 'in said'thimble, and a pin projecting outwardly from the casing adapted to enter the bayonet slot of the socket, said pin passing through said material and touching said thimble whereby to effect electrical connectionthereto.

3. A quick-detachable mercury` switch adapted for insertion i'nto a bayonet-slotted socket having a single central contact, said switch. comprising, in combination, a casing ot insulating material composed of'two sections forming an elongated chamber within the casing, mercury insa/id chamber, a single contact yat, one end of the casing adapted to engage electrically the central contact of the. socket, an annular contact in the casing near the irst contact, and a metallic pin projecting 'l outwardly, from the A casing adapted to enterv .the bayonet slot ofthe socket, said pin passing through s aid casing to said annular contact to serve as one connection to `said switch.

In testimony whereof, I have hereunto affixed my signature.

ROGER L. KNUrssoN. 

